Bhagavad Gita, Chapter 18, Verse 36-37

And now hear from Me, O bull of the Bhâratas, of the threefold happiness. That happiness which one learns to enjoy by habit, and by which one comes to the end of pain; that which is like poison at first, but like nectar at the end; that happiness is declared to be Sâttvika, born of the translucence of intellect due to Self-realisation.

Krishna shifts here to a real, final category, happiness itself, after covering action, performer, intellect, and determination, and names it as starting hard and ending sweet, the opposite order most people expect.

This verse signals a real transition toward the ultimate goal behind everything discussed so far, actual happiness, tied to a pure, self-knowing intellect. This isn't instant gratification, it's happiness earned through real patience, difficulty now for real reward later.